Field of the Invention
The invention relates to a surface temperature sensor, and more particularly to a temperature sensor comprising a flexible printed circuit (FPC) or flexible flat cable (FFC) or conducting wire comprising two or more rows of single calendaring wires prepared by thin film hot pressing technology.
Description of the Related Art
A thermal resistance temperature sensor includes a thin film type temperature sensor and a negative temperature coefficient (NTC) or positive temperature coefficient (PTC) temperature sensor. A typical thin film temperature sensor is formed by packing a bare die type thermistor within a thin film, and soldering a thermistor pin and a conducting wire together by a tin solder. Because the melting temperature of the tin solder is approximately 140° C., in case the temperature exceeds 140° C., the connection between the thermistor pin and the conducting wire tends to disconnect due to the melting of the tin solder, thereby resulting in the failure of temperature measurement. Besides, the thin film temperature sensor is short and needs to be connected to a connecting wire, and the connecting part must be insulated. Thus, the service environment and application range of the thin film temperature sensor are largely restricted.
The thermistor temperature sensor utilizes epoxy resin to pack the NTC or PTC thermistor inside a casing, and a terminal or a jack is formed at the rear part of the sensor. The manufacture process is complex, and problems easily occur including a poor contact or disconnection of the thermistor temperature sensor resulting from insufficient terminal tension, inadequate high voltage, and variance of resistance value of the thermistor due to poor glue seal and line control failures.